Results for "Michael Volpp"

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Trajectory-Based Off-Policy Deep Reinforcement LearningMay 14 2019Policy gradient methods are powerful reinforcement learning algorithms and have been demonstrated to solve many complex tasks. However, these methods are also data-inefficient, afflicted with high variance gradient estimates, and frequently get stuck ... More
Meta-Learning Acquisition Functions for Bayesian OptimizationApr 04 2019Many practical applications of machine learning require data-efficient black-box function optimization, e.g., to identify hyperparameters or process settings. However, readily available algorithms are typically designed to be universal optimizers and ... More
Meta-Learning Acquisition Functions for Bayesian OptimizationApr 04 2019Apr 09 2019Many practical applications of machine learning require data-efficient black-box function optimization, e.g., to identify hyperparameters or process settings. However, readily available algorithms are typically designed to be universal optimizers and ... More
Meta-Learning Acquisition Functions for Bayesian OptimizationApr 04 2019May 28 2019Many practical applications of machine learning, such as tuning hyperparameters or process settings, rely on data-efficient black-box function optimization. Readily available algorithms are typically designed to be universal optimizers and, thus, often ... More
A Worst-case Bound for Topology Computation of Algebraic CurvesApr 08 2011Computing the topology of an algebraic plane curve $\mathcal{C}$ means to compute a combinatorial graph that is isotopic to $\mathcal{C}$ and thus represents its topology in $\mathbb{R}^2$. We prove that, for a polynomial of degree $n$ with coefficients ... More
Comparison between step strains and slow steady shear in a bubble raftDec 20 2004We report on a comparison between stress relaxations after an applied step strain and stress relaxations during slow, continuous strain in a bubble raft. A bubble raft serves as a model two-dimensional foam and consists of a single layer of bubbles on ... More
Evaluation of Contactless Smartcard AntennasJul 23 2015This report summarizes the results of our evaluation of antennas of contactless and dual interface smartcards and our ideas for user-switchable NFC antennas. We show how to disassemble smartcards with contactless capabilities in order to obtain the bare ... More
The periodic Floer homology of a Dehn twistOct 04 2004May 02 2005The periodic Floer homology of a surface symplectomorphism, defined by the first author and M. Thaddeus, is the homology of a chain complex which is generated by certain unions of periodic orbits, and whose differential counts certain embedded pseudoholomorphic ... More
A Variant of K-theory: K_{+-}Feb 11 2003We describe a variant of K-theory for spaces with involution, built from vector bundles which are sent to their negative under the involution.
Logic Programming with Graph Automorphism: Integrating naut with Prolog (Tool Description)Jul 17 2016Aug 01 2016This paper presents the plnauty~library, a Prolog interface to the nauty graph-automorphism tool. Adding the capabilities of nauty to Prolog combines the strength of the "generate and prune" approach that is commonly used in logic programming and constraint ... More
Slow Steady-Shear of Plastic Bead RaftsOct 12 2004Experimental measurements of the response of a two dimensional system of plastic beads subjected to steady shear are reported. The beads float at the surface of a fluid substrate and are subjected to a slow, steady-shear in a Couette geometry. The flow ... More
Asymmetric response of a jammed plastic bead raftMay 18 2006Fluctuation-dissipation relations have received significant attention as a potential method for defining an effective temperature in nonequilibrium systems. The successful development of an effective temperature would be an important step in the application ... More
Examples of nonpolygonal limit shapes in i.i.d. first-passage percolation and infinite coexistence in spatial growth modelsSep 13 2010Mar 13 2013We construct an edge-weight distribution for i.i.d. first-passage percolation on $\mathbb{Z}^2$ whose limit shape is not a polygon and whose extreme points are arbitrarily dense in the boundary. Consequently, the associated Richardson-type growth model ... More
Group analysis of differential equations and generalized functionsDec 28 1999We present an extension of the methods of classical Lie group analysis of differential equations to equations involving generalized functions (in particular: distributions). A suitable framework for such a generalization is provided by Colombeau's theory ... More
Interface dynamics in discrete forward-backward diffusion equationsApr 05 2013We study the motion of phase interfaces in a diffusive lattice equation with bistable nonlinearity and derive a free boundary problem with hysteresis to describe the macroscopic evolution in the parabolic scaling limit. The first part of the paper deals ... More
What the characters of irreducible subrepresentations of Jordan cells can tell us about LCFTJul 22 2013Jan 04 2014In this article, we review some aspects of logarithmic conformal field theories which can be inferred from the characters of irreducible submodules of indecomposable modules. We will mainly consider the W(2,2p-1,2p-1,2p-1) series of triplet algebras and ... More
An algorithm for quantifying dependence in multivariate data setsJul 04 2012Sep 27 2012We describe an algorithm to quantify dependence in a multivariate data set. The algorithm is able to identify any linear and non-linear dependence in the data set by performing a hypothesis test for two variables being independent. As a result we obtain ... More
Hysteresis and phase transitions in a lattice regularization of an ill-posed forward-backward diffusion equationOct 18 2016We consider a lattice regularization for an ill-posed diffusion equation with trilinear constitutive law and study the dynamics of phase interfaces in the parabolic scaling limit. Our main result guarantees for a certain class of single-interface initial ... More
Stopping Active Learning based on Predicted Change of F Measure for Text ClassificationJan 26 2019During active learning, an effective stopping method allows users to limit the number of annotations, which is cost effective. In this paper, a new stopping method called Predicted Change of F Measure will be introduced that attempts to provide the users ... More
The role of blood circulatory system in thermal regulation of animals explained by entropy production analysisAug 16 2013A novel model of thermal regulation of homoeothermic animals has been implemented. The model is based on a non-equilibrium thermodynamic approach which introduces entropy balance and the rate of entropy generation as a formulation of The Second Law. The ... More
Ab-initio wave-length dependent Raman spectra: Placzek approximation and beyondJun 11 2018Jun 13 2019We analyze how to obtain non-resonant and resonant Raman spectra within the Placzek as well as the Albrecht approximation. Both approximations are derived from the matrix element for light scattering by application of the Kramers, Heisenberg and Dirac ... More
A note on Neumann problems on graphsMar 22 2018We discuss Neumann problems for self-adjoint Laplacians on (possibly infinite) graphs. Under the assumption that the heat semigroup is ultracontractive we discuss the unique solvability for non-empty subgraphs with respect to the vertex boundary and provide ... More
Hysteresis and phase transitions in a lattice regularization of an ill-posed forward-backward diffusion equationOct 18 2016Aug 06 2017We consider a lattice regularization for an ill-posed diffusion equation with trilinear constitutive law and study the dynamics of phase interfaces in the parabolic scaling limit. Our main result guarantees for a certain class of single-interface initial ... More
Colored Khovanov-Rozansky homology for infinite braidsSep 19 2017We show that the limiting unicolored $\mathfrak{sl}(N)$ Khovanov-Rozansky chain complex of any infinite positive braid categorifies a highest-weight projector. This result extends an earlier result of Cautis categorifying highest-weight projectors using ... More
CPT and Other Symmetries in String/M TheorySep 20 2004Feb 05 2005We initiate a search for non-perturbative consistency conditions in M theory. Some non-perturbative conditions are already known in Type I theories; we review these and search for others. We focus principally on possible anomalies in discrete symmetries. ... More
Linear programming methods for exponential dominationJan 19 2018For a graph $G,$ we consider $D \subset V(G)$ to be a porous exponential dominating set if $1 \le \sum_{d \in D}$ $\left( \tfrac{1}{2} \right)^{dist(d,v) -1}$ for every $v \in V(G),$ where $dist(d,v)$ denotes the length of the shortest $dv$ path. The ... More
Scaling of the diffraction measure of $k$-free integers near the originMar 30 2019Asymptotics are derived for the scaling of the total diffraction intensity for the set of $k$-free integers near the origin, which is a measure for the degree of patch fluctuations.
On exponential domination of the consecutive circulant graphDec 14 2017For a graph $G,$ we consider $D \subset V(G)$ to be a porous exponential dominating set if $1\le \sum_{d \in D}$ $\left( \frac{1}{2} \right)^{\text{dist}(d,v) -1}$ for every $v \in V(G),$ where dist$(d,v)$ denotes the length of the smallest $dv$ path. ... More
Open Mobile API: Accessing the UICC on Android DevicesJan 12 2016This report gives an overview of secure element integration into Android devices. It focuses on the Open Mobile API as an open interface to access secure elements from Android applications. The overall architecture of the Open Mobile API is described ... More
On Covert Acoustical Mesh Networks in AirJun 04 2014Covert channels can be used to circumvent system and network policies by establishing communications that have not been considered in the design of the computing system. We construct a covert channel between different computing systems that utilizes audio ... More
Root Refinement for Real PolynomialsApr 07 2011Jun 12 2013We consider the problem of approximating all real roots of a square-free polynomial $f$. Given isolating intervals, our algorithm refines each of them to a width of $2^{-L}$ or less, that is, each of the roots is approximated to $L$ bits after the binary ... More
A linear programming method for exponential dominationJan 19 2018Mar 01 2018For a graph $G,$ the set $D \subseteq V(G)$ is a porous exponential dominating set if $1 \le \sum_{d \in D} \left( 2 \right)^{1-dist(d,v)}$ for every $v \in V(G),$ where $dist(d,v)$ denotes the length of the shortest $dv$ path. The porous exponential ... More
A natural probability measure derived from Stern's diatomic sequenceJun 01 2017Mar 15 2018Stern's diatomic sequence with its intrinsic repetition and refinement structure between consecutive powers of $2$ gives rise to a rather natural probability measure on the unit interval. We construct this measure and show that it is purely singular continuous, ... More
Vacuum instability and gravitational collapseNov 06 2002Dec 11 2002We argue that $(0,1)$ heterotic string models with 4 non-heterotic spacetime dimensions may provide an instability of the vacuum to gravitational polarization in globally strong gravitational fields. This instability would be triggered during gravitational ... More
SL(n,C)- Representation spaces of Knot GroupsFeb 11 2016The first part of this article is a general introduction to the the theory of representation spaces of discrete groups into SL(n,C). Special attention is paid to knot groups. In Section 2 we discuss the difference between the tangent space at the representation ... More
The Non-Existent Complex 6-SphereOct 25 2016The possible existence of a complex structure on the 6-sphere has been a famous unsolved problem for over 60 years. In that time many ``solutions'' have been put forward, in both directions. Mistakes have always been found. In this paper I present a short ... More
Boundary form factors in the Smirnov--Fateev model with a diagonal boundary $S$ matrixJan 07 2008The boundary conditions with diagonal boundary $S$ matrix and the boundary form factors for the Smirnov--Fateev model on a half line has been considered in the framework of the free field representation. In contrast to the case of the sine-Gordon model, ... More
Acoustic methods for measuring bullet velocityDec 27 2008This article describes two acoustic methods to measure bullet velocity with an accuracy of 1% or better. In one method, a microphone is placed within 0.1 m of the gun muzzle and a bullet is fired at a steel target 45 m away. The bullet's flight time is ... More
Sheaf and cosheaf methods for analyzing multi-model systemsApr 15 2016There is an interplay between models, specified by variables and equations, and their connections to one another. This dichotomy should be reflected in the abstract as well. Without referring to the models directly -- only that a model consists of spaces ... More
Intrinsic flat convergence with bounded Ricci curvatureMay 13 2014Apr 24 2015In this paper we address the relationship between Gromov-Hausdorff limits and intrinsic flat limits of complete Riemannian manifolds. In \cite{SormaniWenger2010, SormaniWenger2011}, Sormani-Wenger show that for a sequence of Riemannian manifolds with ... More
Generalization bound for kernel similarity learningOct 12 2016Similarity learning has received a large amount of interest and is an important tool for many scientific and industrial applications. In this framework, we wish to infer the distance (similarity) between points with respect to an arbitrary distance function ... More
On the autonomous metric on groups of Hamiltonian diffeomorphisms of closed hyperbolic surfacesMay 13 2013May 30 2014Let $\Sigma_g$ be a closed hyperbolic surface of genus $g$ and let $Ham(\Sigma_g)$ be the group of Hamiltonian diffeomorphisms of $\Sigma_g$. The most natural word metric on this group is the autonomous metric. It has many interesting properties, most ... More
Quasi-morphisms and L^p-metrics on groups of volume-preserving diffeomorphismsOct 14 2011Sep 03 2012Let M be a smooth compact connected oriented manifold of dimension at least two endowed with a volume form. We show that every homogeneous quasi-morphism on the identity component $Diff_0(M,vol)$ of the group of volume preserving diffeomorphisms of M, ... More
Isomorphisms of Hilbert C*-Modules and $*$-Isomorphisms of Related Operator C*-AlgebrasMay 09 1995Let $\cal M$ be a Banach C*-module over a C*-algebra $A$ carrying two $A$-valued inner products $< .,. >_1$, $<.,. >_2$ which induce equivalent to the given one norms on $\cal M$. Then the appropriate unital C*-algebras of adjointable bounded $A$-linear ... More
A half-normal distribution scheme for generating functions and the unexpected behavior of Motzkin pathsMay 10 2016We present an extension of a theorem by Michael Drmota and Mich\`ele Soria [Images and Preimages in Random Mappings, 1997] that can be used to identify the limiting distribution for a class of combinatorial schemata. This is achieved by determining analytical ... More
"Did I Say Something Wrong?" A Word-Level Analysis of Wikipedia Articles for Deletion DiscussionsMar 25 2016This thesis focuses on gaining linguistic insights into textual discussions on a word level. It was of special interest to distinguish messages that constructively contribute to a discussion from those that are detrimental to them. Thereby, we wanted ... More
Processing Complex Sentences in the Centering FrameworkMay 14 1996We extend the centering model for the resolution of intra-sentential anaphora and specify how to handle complex sentences. An empirical evaluation indicates that the functional information structure guides the search for an antecedent within the sentence. ... More
Never Look Back: An Alternative to CenteringJun 25 1998I propose a model for determining the hearer's attentional state which depends solely on a list of salient discourse entities (S-list). The ordering among the elements of the S-list covers also the function of the backward-looking center in the centering ... More
Measuring the Size of Large No-Limit Poker GamesFeb 27 2013Mar 07 2013In the field of computational game theory, games are often compared in terms of their size. This can be measured in several ways, including the number of unique game states, the number of decision points, and the total number of legal actions over all ... More
Large-Scale Reasoning with OWLFeb 14 2016With the growth of the Semantic Web in size and importance, more and more knowledge is stored in machine-readable formats such as the Web Ontology Language OWL. This paper outlines common approaches for efficient reasoning on large-scale data consisting ... More
Non-Abelian twisted kinks in chiral Gross-Neveu model with isospinDec 12 2015Apr 05 2016The two-dimensional, massless Gross-Neveu model with Nc colors and SU(2) isospin is studied analytically in the large Nc limit. The chiral SU(2)L X SU(2)R symmetry is broken spontaneously in the vacuum. Twisted kinks connecting two arbitrary points on ... More
Space-Efficient Latent ContractsApr 08 2016Jun 01 2016Standard higher-order contract monitoring breaks tail recursion and leads to space leaks that can change a program's asymptotic complexity. Space efficient semantics restore tail recursion and bound the amount of space used by contacts. Space efficient ... More
A quasi-exactly solvable model: two charges in a magnetic field, subject to a non-Coulomb mutual interactionSep 24 2015We extend the class of QM problems which permit for quasi-exact solutions. Specifically, we consider planar motion of two interacting charges in a constant uniform magnetic field. While Turbiner and Escobar-Ruiz (2013) addressed the case of the Coulomb ... More
Graphics Turing TestMar 31 2006We define a Graphics Turing Test to measure graphics performance in a similar manner to the definition of the traditional Turing Test. To pass the test one needs to reach a computational scale, the Graphics Turing Scale, for which Computer Generated Imagery ... More
The Universal Severi Variety of Rational Curves on K3 SurfacesOct 19 2011We investigate the universal Severi variety of rational curves on K3 surfaces, which parametrises irreducible rational curves in a fixed class on varying K3 surfaces of fixed genus. We investigate the conjecuted irreducibility of this space in the case ... More
Equivariant Cohomology and Representations of the Symmetric GroupDec 21 2000A cohomological study is made of an equivariant map betwen the configuration space of n points in space and the flag manifold of U(n).
Taubes's proof of the Weinstein conjecture in dimension threeJun 13 2009Sep 22 2009This is an introduction to Taubes's proof of the Weinstein conjecture, written for the AMS Current Events Bulletin. It is intended to be accessible to nonspecialists, so much of the article is devoted to background and context.
Non Super-Cell SuperConductivity Of High Tc MaterialsMay 20 2010Recently we have described materials interface transport coupling rigorously utilizing NEGF nonequilibrium Green's functions, and have discussed the Hamiltonian terms that from Green's theorem and boundary conditions can be rewritten as Self Energy. We ... More
Further Exploration of Riemann's Functional EquationSep 10 2016A previous exploration of the Riemann functional equation that focussed on the critical line, is extended over the complex plane. Significant results include a simpler derivation of the fundamental equation developed previously, and its generalization ... More
Warm Gas at High Redshift - Clues to Gravitational Structure Formation from Optical Spectroscopy of Lyman Alpha Absorption SystemsDec 01 1995We discuss the effects of gravitational collapse on the shape of absorption line profiles for low column density (log N(HI) < 14) Lyman Alpha forest clouds and argue by comparison with cosmological simulations that Lyman alpha forest observations show ... More
Large NSep 08 2005Some mysterious features of the strong interactions become easily understood if our usual QCD with N=3 is `close to' SU(oo) and if the latter theory is confining. N=oo theories are theoretically simpler; in particular there has been much progress in constructing ... More
Twenty Hirsch index variants and other indicators giving more or less preference to highly cited papersMay 28 2010The Hirsch index or h-index is widely used to quantify the impact of an individual's scientific research output, determining the highest number h of a scientist's papers that received at least h citations. Several variants of the index have been proposed ... More
How much do different ways of calculating percentiles influence the derived performance indicators? - A case studyFeb 26 2013Bibliometric indicators can be determined by comparing specific citation records with the percentiles of a reference set. However, there exists an ambiguity in the computation of percentiles because usually a significant number of papers with the same ... More
Uncertainties and Ambiguities in Percentiles and how to Avoid ThemMay 16 2012The recently proposed fractional scoring scheme is used to attribute publications to percentile rank classes. It is shown that in this way uncertainties and ambiguities in the evaluation of percentile ranks do not occur. Using the fractional scoring the ... More
Inconsistencies of Recently Proposed Citation Impact Indicators and how to Avoid ThemFeb 17 2012Apr 04 2012It is shown that under certain circumstances in particular for small datasets the recently proposed citation impact indicators I3(6PR) and R(6,k) behave inconsistently when additional papers or citations are taken into consideration. Three simple examples ... More
A Case Study of the Modified Hirsch Index hm Accounting for Multiple Co-authorsMar 28 2009J. E. Hirsch (2005) introduced the h-index to quantify an individual's scientific research output by the largest number h of a scientist's papers, that received at least h citations. This so-called Hirsch index can be easily modified to take multiple ... More
Stellar population properties of the most massive globular clusters and ultra-compact dwarf galaxies of the Fornax clusterDec 23 2015Most ultra-compact dwarf galaxies (UCDs) and very massive globular clusters reside in nearby galaxy clusters or around nearby giant galaxies. Due to their distance (>Mpc) and compactness (r_eff<100pc) they are barely resolved, and thus it is difficult ... More
Reducing the Error FloorJun 20 2007We discuss how the loop calculus approach of [Chertkov, Chernyak '06], enhanced by the pseudo-codeword search algorithm of [Chertkov, Stepanov '06] and the facet-guessing idea from [Dimakis, Wainwright '06], improves decoding of graph based codes in the ... More
Floer homology in disc bundles and symplectically twisted geodesic flowsJul 10 2008We show that if K: P \to R is an autonomous Hamiltonian on a symplectic manifold (P,\Omega) which attains 0 as a Morse-Bott nondegenerate minimum along a symplectic submanifold M, and if c_1(TP)|_M vanishes in real cohomology, then the Hamiltonian flow ... More
J/ψProduction in Direct and Resolved Photon CollisionsApr 29 2003The production of J/Psi mesons in photon photon collisions allows for a test of factorization in color-octet processes as predicted by NRQCD and observed at the Tevatron. We calculate the cross sections for J/Psi production with direct and resolved photons, ... More
Theory of hard photoproductionJun 19 2002The present theoretical knowledge about photons and hard photoproduction processes, i.e. the production of jets, light and heavy hadrons, quarkonia, and prompt photons in photon-photon and photon-hadron collisions, is reviewed. Virtual and polarized photons ... More
Hofer's length spectrum of symplectic surfacesNov 09 2014Following a question of F. Le Roux, we consider a system of invariants $l_A : H_1(M; \mathbb{Z})\to\mathbb{R}$ of a symplectic surface $M$. These invariants compute the minimal Hofer energy needed to translate a disk of area $A$ along a given homology ... More
Lectures on Nehari's Theorem on the PolydiskJan 12 2006We give a leisurely proof of a result of Ferguson--Lacey (math.CA/0104144) and Lacey--Terwelleger (math.CA/0601192) on a Nehari theorem for "little" Hankel operators on a polydisk. If H_b is a little Hankel operator with symbol b on product Hardy space ... More
Thermodynamics of Time MachinesFeb 08 2013In this note, a brief review of the consistent state approach to systems containing closed timelike curves or similar devices is given, and applied to the well known thermodynamic problem of Maxwell's demon. The 'third party paradox' for acausal systems ... More
Experimental Test of the Final State HypothesisMar 13 2014The black hole final state projection model, also known as the Horowitz-Maldacena model has garnished new interest due to the current debate over black hole firewalls. The nonlinear quantum mechanics of post-selection preserves information and avoids ... More
Conical tip in frozen water dropsApr 17 2014A theory is presented for the formation of a conical tip in water drops that are frozen on a flat surface below freezing temperature. For the known ice to water density ratio r = .917, the angle of aperture of this cone is found to be {\theta} = 33.550, ... More
Critique of "Quantum Enigma:Physic encounters Consciousness"May 14 2007May 15 2007The central claim that understanding quantum mechanics requires a conscious observer, which is made made by B. Rosenblum and F. Kuttner in their book "Quantum Enigma: Physics encounters consciousnes", is shown to be based on various misunderstandings ... More
The evolution of radiation towards thermal equilibrium: A soluble model which illustrates the foundations of Statistical MechanicsMay 10 2003In 1916 Einstein introduced the first rules for a quantum theory of electromagnetic radiation, and he applied them to a model of matter in thermal equilibrium with radiation to derive Planck's black-body formula. Einstein's treatment is extended here ... More
The Reception of Newton's PrincipiaMar 23 2015Newton's Principia, when it appeared in 1687, was received with the greatest admiration, not only by the foremost mathematicians and astronomers in Europe, but also by philosophers like Voltaire and Locke and by members of the educated public. In this ... More
Hooke's memorandum on the development of orbital dynamicsApr 13 2005I discuss a memorandum entitled " A True state of the Case and Controversy between Sir Isaak Newton and Dr. Robert Hooke as the Priority of that Noble Hypothesis of motion of ye Planets about ye Sun as their Centers", where Hooke summarizes his life long ... More
Democratic Superstring Field Theory: Gauge FixingOct 08 2010Mar 22 2011We show that a partial gauge fixing of the NS sector of the democratic-picture superstring field theory leads to the non-polynomial theory. Moreover, by partially gauge fixing the Ramond sector we obtain a non-polynomial fully RNS theory at pictures 0 ... More
Uncertainty in hybrid gravitational waveforms: Optimizing initial orbital frequencies for binary black-hole simulationsMar 25 2011Aug 31 2011A general method is presented for estimating the uncertainty in hybrid models of gravitational waveforms from binary black-hole systems with arbitrary physical parameters, and thence the highest allowable initial orbital frequency for a numerical-relativity ... More
The Future of Nuclear Energy: Facts and Fiction Chapter I: Nuclear Fission Energy TodayAug 05 2009Nuclear fission energy is considered to be somewhere between the holy grail, required to solve all energy worries of the human industrialized civilization, and a fast path directly to hell. Discussions about future energy sources and the possible contribution ... More
The End of Cheap UraniumJun 18 2011Jun 21 2011Historic data from many countries demonstrate that on average no more than 50-70% of the uranium in a deposit could be mined. An analysis of more recent data from Canada and Australia leads to a mining model with an average deposit extraction lifetime ... More
The Future of Nuclear Energy: Facts and Fiction Chapter II: What is known about Secondary Uranium Resources?Aug 21 2009During 2009 nuclear power plants, with a capacity of 370 GWe, will produce roughly 14% of the worldwide electric energy. About 65000 tons of natural uranium equivalent are required to operate these reactors. For 15 years on average only 2/3 of this fuel ... More
On the structure of universal differentiability setsJul 20 2016We prove that universal differentiability sets in Euclidean spaces possess distinctive structural properties. Namely, we show that any universal differentiability set contains a `kernel' in which the points of differentiability of each Lipschitz function ... More
Temporal Modulation of the Control Parameter in Electroconvection in the Nematic Liquid Crystal I52Jul 18 2000I report on the effects of a periodic modulation of the control parameter on electroconvection in the nematic liquid crystal I52. Without modulation, the primary bifurcation from the uniform state is a direct transition to a state of spatiotemporal chaos. ... More
One-dimensional classical adjoint SU(2) Coulomb GasJan 21 1997The equation of state of a one-dimensional classical nonrelativistic Coulomb gas of particles in the adjoint representation of SU(2) is given. The problem is solved both with and without sources in the fundamental representation at either end of the system. ... More
Nonrelativistic Particle in Free Random Gauge BackgroundApr 02 1996The problem of a nonrelativistic particle with an internal color degree of freedom, with and without spin, moving in a free random gauge background is discussed. Freeness is a concept developed recently in the mathematical literature connected with noncommuting ... More
Topological properties of the SU(3) random vortex world-surface modelJun 06 2009The random vortex world-surface model is an infrared effective model of Yang-Mills dynamics based on center vortex degrees of freedom. These degrees of freedom carry topological charge through writhe and self-intersection of their world-surfaces. A practical ... More
Center vortex model for the infrared sector of SU(3) Yang-Mills theory -- baryonic potentialJun 15 2004Jun 28 2004The baryonic potential in the framework of the SU(3) random vortex world-surface model is evaluated for a variety of static color source geometries. For comparison, carefully taking into consideration the string tension anisotropy engendered by the hypercubic ... More
On the spectrum of QCD(1+1) with large numbers of flavours N_F and colours N_C near N_F/N_C = 0Jan 09 2001QCD(1+1) in the limit of a large number of flavours N_F and a large number of colours N_C is examined in the small N_F/N_C regime. Using perturbation theory in N_F/N_C, stringent results for the leading behaviour of the spectrum departing from N_F/N_C ... More
QCD_{1+1} at large N_F and N_CDec 19 1994QCD in 1+1 dimensions is examined in the limit of a large number of colors and flavors. The Hamiltonian matrix is given in a Fock space spanned by 't Hooft meson states and, for the case of zero fermion mass, a submatrix is diagonalized numerically to ... More
Resummation of angular dependent corrections in spontaneously broken gauge theoriesAug 27 2001Recent investigations of electroweak radiative corrections have revealed the importance of higher order contributions in high energy processes, where the size of typical corrections can exceed those associated with QCD considerably. Beyond one loop, only ... More
The Ages, Masses, Evolution and Kinematics of Mira variableDec 01 2008Evidence on the ages and masses of Mira variables is reviewed. Period increases with increasing initial mass. Miras of logP about 3.0 have initial masses of near 4 solar masses. It is suggestd that the apparent gap in the LMC PL relation at about this ... More
Is There a String Theory Landscape: Some Cautionary NotesFeb 13 2004Feb 17 2004There is evidence that string theory possesses a large discretuum of stable and/or metastable ground states, with zero or four supersymmetries in four dimensions. I discuss critically the nature of this evidence. Assuming this "landscape" exists, anthropic ... More
Dark Matter and Dark Energy: A Physicist's PerspectiveJul 30 2001For physicists, recent developments in astrophysics and cosmology present exciting challenges. We are conducting "experiments" in energy regimes some of which will be probed by accelerators in the near future, and others which are inevitably the subject ... More
TASI Lectures on The Strong CP ProblemNov 29 2000Nov 30 2000These lectures discuss the $\theta$ parameter of QCD. After an introduction to anomalies in four and two dimensions, the parameter is introduced. That such topological parameters can have physical effects is illustrated with two dimensional models, and ... More
Electroweak Baryogenesis: An Overview (Where are We Now?)Jun 12 1992Jun 16 1992It now seems plausible that the observed baryon asymmetry may have been produced at the electroweak phase transition. We review the considerations which lead to this conclusion, focusing on the obstacles to making reliable estimates. These arise from ... More
Labelled transition systems as a Stone spaceDec 15 2004Mar 08 2006A fully abstract and universal domain model for modal transition systems and refinement is shown to be a maximal-points space model for the bisimulation quotient of labelled transition systems over a finite set of events. In this domain model we prove ... More